Great question. I've been wondering the same thing. I recently discovered the RoundFlash, http://roundflash.com/, which looks quite promising. (It's now available from B&H.)
I mostly shoot available light, but when a flash is a must or for mobile portrait photos, the concept of a near soft box size ring flash is intriguing. But, I'm having trouble accepting any light source that close to the lens for people shots. I fear the ring flash will still look a bit flat.
Hotshoe mount ring flashes are usually very low powered, intended for close-up macro/medical work. The ones that attach to your existing Speedlight can be OK, YMMV with the different types available. An ongoing concern with the bolt-on attachments is the additional weight/strain on the hotshoe mount. Still, for occasional use they can be a viable choice. I'd be chasing around for reviews.
I bought a ray flash from eBay and I was surprised at how cheap it felt. I attached it and there was a crack in it and the seller said it wasn't there before. I returned it, but as far as that was concerned, I didn't care for how it felt... it just seemed awkward.
Those add-on ringflash things for your speedlight are big, clunky and easily broken, to say nothing about the loss of light while it is bouncing around inside the unit.
For the same or less money, you can buy a proper ringflash from many of the Chinese websites and the one I got really works well. It might be fully manual, but you can easily adjust it from the camera menu, and for around $130 - it's fantastic.
Works well for portraits and gives a very nice circular spark in the subject's eyes.
If you want slightly different lighting from one side to the other, you can just drape bits of tissue over one side of it.
That way, it gives nice slight shadowing to one side of the face.
... you can buy a proper ringflash from many of the Chinese websites and the one I got really works well. It might be fully manual, but you can easily adjust it from the camera menu, and for around $130 - it's fantastic.
Are you referring to the low guide number flashes like the YONGNUO YN-14EX Macro Ring Flash (Guide Number -14)
or Godox ML-150 Photo Macro Ring Flash (Guide Number-10)?
Which one did you get? Can you link us to it?
I picked up a used canon ring flash. It also doubles as a trigger for remote speedlights so there is some value there for wedding or portraits use...particularly if you have a 5d3 or other camera without an integrated flash. I've found that the full front on ring produces a pretty harsh lighting. I usually use fractional power or shift the power to the left or right tube. I then let the speedlights provide the main lighting.
It can be run in many ways. One way it is used is as the primary light outdoors (with a Vagabond Mini Lithium power pack) and the sun as a rim. Another way is for that shadowless indoor studio look. Or you can use it simply as a fill light with a primary light somewhere else off camera. Or you can just run it on a lightstand off camera as either your primary or fill/rim light (several attachments, e.g. moon unit, grid, etc).
A friend of mine has the Roundflash. It's an interesting unit and he had luck with it indoors at conventions (e.g. Glamourcon) using a Nikon FF and a 105mm. Not sure which Nikon SB he used.
Nice tool.
I have the roundflash.
You have to be close, around 1,5m; then it works fine.
And yes, its getting heavier and the camera is more tricky to hold.